the other thing to be aware of with 650 wheels is that most people are on 700c... so the issue is that if you are out somewhere and have a flat... you can't borrow a tube/tire from someone.

I was riding the Cool Breeze Century in Aug with a friend... she blew out the sidewall of her rear tire at mile 15... we made it to the SAG and they had tires! Uh oh... they had 700c tires NO 650! We sat waiting for an hour til her husband drove in with a tire for her... big, big bummer. Later that ride we saw a rider off the side of the road... he had already had 2 flats and was out of tubes... I gave him one of my extras and he was able to complete his ride... because he was 700 it was possible for me to loan him one...

just something to think about... with 650 you have to be super prepared...